Influences of phase delay shifts of light and food restriction on blood pressure and heart rate in telemetry monitored rats

Effects of phase delay shifts (PDS) of light in combination with moderately increased salt intake (SL) (2%) or time restriction of food (FR) during the light-time (passive phase) on heart rate (HR), blood pressure (BP) and locomotor activity (LA) in radiotelemetry-measured rats were evaluated. PDS decreased amplitude and spectral power of circadian oscillations of HR, BP and LA. Moderately increased SL did not interfere with the circadian rhythmicity of HR, BP or LA. A prominent decrease in amplitude and spectral power of circadian oscillations was observed if food was available during the lighttime. Combination of PDS with FR split cardiovascular and behavioural parameters. In conclusion, food availability during the light-time in combination with PDS decreased amplitude and spectral power of circadian oscillations of BP, HR and LA more than PDS only. Different response of cardiovascular and behavioural parameters to photic and non-photic stimuli can have consequences for shift workers.